My Long-haul Saturn project

[Jooshmeister]

I have plans on putting a turbocharger in my little 2000 SL2.

So far I have been doing a lot of reading up and studying and the car itself will no longer be my daily driver, which means this car will be a bit of an experiment.

The first step of the experiment was to bring it back up to OE standards and assess just how feasible a small turbo setup would be. This included replacing many of the worn out old parts and upgrading some others.
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Old fuel pump (unknown mileage, >140,000km), old fuel filter (~75,000km)
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All old engine/trans mounts replaced
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Old exhaust replaced with 2.5"

Not shown is the front-end suspension work I've already done (new tires, wheel bearings, lower control arms, CV axles)

The second step was to put in a MS2 and play around with it until I have all of the parts, space and time necessary to commit to the turbo installation. This is the stage that I am at now, and I have to say that I'm learning loads of cool stuff and having fun doing it.

Some things I would appreciate some feedback on are things that have been mentioned in other posts before.

1: How important is it to run a fuel return line? Honestly, we are talking about a small turbo and a small amount of boost (<8PSI).
2: What is the best way to incorporate a wide-band O2 sensor in the setup? Is it absolutely necessary?
3: I know people would advise me to keep the original PCM in tandem with the new Megasquirt 2. What happens if I don't?
4: The engine will be receiving some work before I boost it, but I'm not sure how far I should go with this. Bear in mind that this is essentially just practice for honing my mechanical skills. Should I do the engine work myself (and have to wait with the turbo until next summer) or should I just go with it now?

I've already posted a thread asking some of these questions, but perhaps it was in the wrong place. I'd really appreciate constructive comments, but feel free to unload on me too.

Anyway, I'll keep my story up to date for anyone who cares to follow.

[leadfootny]

I'll answer what I can....

2. Yes, a wideband is absolutely necessary. You really don't know whats going on fuel/air wise without it. Placement is dependent on your exhaust setup and if you are turbo/NA. The distance between the sensor and either the turbo or exhaust is slightly different..I am not sure if it is significant but too close and you'll burn up the sensor in short order.
3. I think most ppl keep the stock pcm to run gauges. If you eliminate it, you'd need standalone gauges or converters to interpret the signals.
4. Depends on how beat your motor is and how much ya plan on beating on it. A whooped motor probably won't last long boosted. If this is your first foray into motor building and crap, I'd start by getting the motor into good condition first. I'd definitely do all the work yourself.
Good luck!

[siris]

Your best bet is to ad a return line.

As boost rises, you change the pressure differential across the injector, which changes the flow rate.

Manifold vacuum sucks fuel out, that's why stock they have a vacuum port on the return style fuel pressure regulator, it reduces fuel pressure based on high vacuum.

Boost is opposite, when there is a positive pressure in the intake manifold, it wants to push fuel back into the injectors, it reduces the amount of fuel coming from the injectors, you won't see a significant amount of fuel reduction at 1-5 psi, but once boost gets to fun levels your essentially pulling fuel, which = boom.